2 files changed, 51 insertions, 0 deletions

diff --git a/src/svm/svm_fifo.c b/src/svm/svm_fifo.c
index f1ac8d49b92..ff941a7a6dd 100644
--- a/src/svm/svm_fifo.c
+++ b/src/svm/svm_fifo.c
@@ -1222,6 +1222,42 @@ svm_fifo_fill_chunk_list (svm_fifo_t * f)
 }
 
 int
+svm_fifo_provision_chunks (svm_fifo_t *f, svm_fifo_seg_t *fs, u32 n_segs,
+			   u32 len)
+{
+  u32 head, tail, n_avail, head_pos, n_bytes, fs_index = 1, clen;
+  svm_fifo_chunk_t *c;
+
+  f_load_head_tail_prod (f, &head, &tail);
+
+  if (f_free_count (f, head, tail) < len)
+    return SVM_FIFO_EFULL;
+
+  n_avail = f_chunk_end (f->end_chunk) - tail;
+
+  if (n_avail < len && f_try_chunk_alloc (f, head, tail, len))
+    return SVM_FIFO_EGROW;
+
+  c = f->tail_chunk;
+  head_pos = (tail - c->start_byte);
+  fs[0].data = c->data + head_pos;
+  fs[0].len = clib_min (c->length - head_pos, len);
+  n_bytes = fs[0].len;
+
+  while (n_bytes < len && fs_index < n_segs)
+    {
+      c = c->next;
+      clen = clib_min (c->length, len - n_bytes);
+      fs[fs_index].data = c->data;
+      fs[fs_index].len = clen;
+      n_bytes += clen;
+      fs_index += 1;
+    }
+
+  return fs_index;
+}
+
+int
 svm_fifo_segments (svm_fifo_t * f, u32 offset, svm_fifo_seg_t * fs,
 		   u32 n_segs, u32 max_bytes)
 {
diff --git a/src/svm/svm_fifo.h b/src/svm/svm_fifo.h
index 4239e9d78ea..2a054526865 100644
--- a/src/svm/svm_fifo.h
+++ b/src/svm/svm_fifo.h
@@ -208,6 +208,21 @@ svm_fifo_chunk_t *svm_fifo_chunk_alloc (u32 size);
  */
 int svm_fifo_fill_chunk_list (svm_fifo_t * f);
 /**
+ * Provision and return chunks for number of bytes requested
+ *
+ * Allocates enough chunks to cover the bytes requested and returns them
+ * in the fifo segment array. The number of bytes provisioned may be less
+ * than requested if not enough segments were provided.
+ *
+ * @param f		fifo
+ * @param fs		array of fifo segments
+ * @param n_segs	length of fifo segments array
+ * @param len		number of bytes to preallocate
+ * @return		number of fifo segments provisioned or error
+ */
+int svm_fifo_provision_chunks (svm_fifo_t *f, svm_fifo_seg_t *fs, u32 n_segs,
+			       u32 len);
+/**
  * Initialize rbtrees used for ooo lookups
  *
  * @param f		fifo